1. Field of the Invention
The field of the invention relates to methods and systems for processing images, and more particularly, to methods and systems for processing x-ray images.
2. Background of the Invention
Radiation therapy involves medical procedures that selectively expose certain areas of a human body, such as cancerous tumors, to doses of radiation. The purpose of the radiation therapy is to irradiate the targeted biological tissue such that undesirable tissue is destroyed. Radiation has also been used to obtain image of tissue for diagnostic or treatment purposes.
In a radiation treatment session, the position and movement of a target tissue can be monitored by an imaging system, such as a fluoroscopic imaging system, while radiation is delivered to the target tissue. This ensures that the target tissue is in a desired position while the radiation is being delivered. However, often soft tissue targets such as a variety of tumors are not visible in x-ray fluoroscopic images. This is due to structures in front or behind the target tissue which are also visible in the x-ray images thus increasing the clutter to the level that the target tissue cannot be distinguished.
Internal radio-opaque markers have been used to aid physicians in identifying a target tissue under fluoroscopic imaging. The radio-opaque markers can be injected or implanted at desired sites within a patient, and they shows up as high contrast features in fluoroscopic images. By observing the positions of the internal radio-opaque markers in fluoroscopic images, a physician can determine a position of a target tissue. However, implantation of markers is intrusive to the patient, and it may not be practical or feasible in all cases.
Accordingly, systems and methods for visualization of internal tissue without use of internal markers would be useful.